The change applies to its BTL limited company mortgage range and the property limit was previously three properties.
The lender said every application was assessed on a case-by-case basis and the removal means that more portfolio landlords can be catered for.
Keith Barber, director of business development at Family BS, said: “Originally, we had a limit on the number of BTLs an SPV could hold, but as the market has developed and matured we have relaxed this.
“Now that more lending is done to company owned BTLs rather than to personal borrowers due to the tax benefits the former enjoy, it makes sense for us to better align this aspect of our personal and limited company lending criteria.”
The lender added that it there is no minimum income for BTL clients and no stress test on background properties held. It has also upped the maximum loan to value to 70 per cent, will accept applications from borrowers up to age of 89 and it will accept expat cases.